If the speculation about Gov. Bob McDonnell’s (R) White House aspirations hadn’t yet reached a fever pitch, they did Friday morning when he endorsed Mitt Romney as his party’s top candidate to go head-to-head with President Barack Obama.

McDonnell told CNBC he hoped the endorsement would buoy Romney ahead of Saturday’s South Carolina primary, where the former Massachusetts governor has struggled in recent days. Once the uncontested GOP frontrunner, Romney has lost some of his luster after two poor debate showings and news he did not, in fact, win the Iowa Caucus. Rivals Newt Gingrich and Rick Santorum have connected with southern voters in a way Romney seemingly has been unable.

“It’s a Southern primary. I’m a Southern governor and I thought I could help the governor by coming out today,” McDonnell told CNBC.